Automated oxygen titration with non-invasive ventilation in hypoxaemic adults with cardiorespiratory disease: a randomised cross-over trial.

BACKGROUND: Closed-loop oxygen control systems automatically adjust the fraction of inspired oxygen (FiO2) to maintain oxygen saturation (SpO2) within a predetermined target range. Their performance with low and high-flow oxygen therapies, but not with non-invasive ventilation, has been established. We compared the effect of automated oxygen on achieving and maintaining a target SpO2 range with nasal high flow (NHF), bilevel positive airway pressure (bilevel) and continuous positive airway pressure (CPAP), in stable hypoxaemic patients with chronic cardiorespiratory disease. METHODS: In this open-label, three-way cross-over trial, participants with resting hypoxaemia (n=12) received each of NHF, bilevel and CPAP treatments, in random order, with automated oxygen titrated for 10 min, followed by 36 min of standardised manual oxygen adjustments. The primary outcome was the time taken to reach target SpO2 range (92%-96%). Secondary outcomes included time spent within target range and physiological responses to automated and manual oxygen adjustments. RESULTS: Two participants were randomised to each of six possible treatment orders. During automated oxygen control (n=12), the mean (±SD) time to reach target range was 114.8 (±87.9), 56.6 (±47.7) and 67.3 (±61) seconds for NHF, bilevel and CPAP, respectively, mean difference 58.3 (95% CI 25.0 to 91.5; p=0.002) and 47.5 (95% CI 14.3 to 80.7; p=0.007) seconds for bilevel and CPAP versus NHF, respectively. Proportions of time spent within target range were 68.5% (±16.3), 65.6% (±28.7) and 74.7% (±22.6) for NHF, bilevel and CPAP, respectively.Manually increasing, then decreasing, the FiO2 resulted in similar increases and then decreases in SpO2 and transcutaneous carbon dioxide (PtCO2) with NHF, bilevel and CPAP. CONCLUSION: The target SpO2 range was achieved more quickly when automated oxygen control was initiated with bilevel and CPAP compared with NHF while time spent within the range across the three therapies was similar. Manually changing the FiO2 had similar effects on SpO2 and PtCO2 across each of the three therapies. TRIAL REGISTRATION NUMBER: ACTRN12622000433707.

Effect of a lower target oxygen saturation range on the risk of hypoxaemia and elevated NEWS2 scores at a university hospital: a retrospective study.

BACKGROUND: The optimal target oxygen saturation (SpO2) range for hospital inpatients not at risk of hypercapnia is unknown. The objective of this study was to assess the impact on oxygen usage and National Early Warning Score 2 (NEWS2) of changing the standard SpO2 target range from 94-98% to 92-96%. METHODS: In a metropolitan UK hospital, a database of electronic bedside SpO2 measurements, oxygen prescriptions and NEWS2 records was reviewed. Logistic regression was used to compare the proportion of hypoxaemic SpO2 values (<90%) and NEWS2 records ≥5 in 2019, when the target SpO2 range was 94-98%; with 2022, when the target range was 92-96%. RESULTS: In 2019, 218 of 224 936 (0.10%) observations on room air and 162 of 11 328 (1.43%) on oxygen recorded an SpO2 <90%, and in 2022, 251 of 225 970 (0.11%) and 233 of 12 845 (1.81%), respectively (risk difference 0.04%, 95% CI 0.02% to 0.07%). NEWS2 ≥5 was observed in 3009 of 236 264 (1.27%) observations in 2019 and 4061 of 238 815 (1.70%) in 2022 (risk difference 0.43%, 0.36% to 0.50%; p<0.001). The proportion of patients using supplemental oxygen with hyperoxaemia (SpO2 100%) was 5.4% in 2019 and 3.9% in 2022 (OR 0.71, 0.63 to 0.81; p<0.001). DISCUSSION: The proportion of observations with SpO2 <90% or NEWS2 ≥5 was greater with the 92-96% range; however, absolute differences were very small and of doubtful clinical relevance, in contrast to hyperoxaemia for which the proportion was markedly less in 2022. These findings support proposals that the British Thoracic Society oxygen guidelines could recommend a lower target SpO2 range.

Skin-to-deltoid-muscle distance at three recommended sites for intramuscular vaccination in a population with obesity: an observational study.

AIM: Worldwide, immunisation guidelines variably locate the deltoid injection site based on anatomical landmarks. This may influence the skin-to-deltoid-muscle distance and therefore the needle length required to achieve intramuscular injection. Obesity is associated with increased skin-to-deltoid-muscle distance, but it is unknown whether the injection site location chosen in individuals with obesity impacts the needle length required for intramuscular injection. The aim of the study was to estimate the differences in skin-to-deltoid-muscle distance between three different vaccine injection sites recommended by the national guidelines of the United States of America (USA), Australia and New Zealand, in obese adults. The study also explored i) the associations between skin-to-deltoid-muscle distance across the three recommended sites with sex, body mass index (BMI), and arm circumference, and ii) the proportion of participants with a skin-to-deltoid-muscle distance >20 millimetres (mm), in whom the standard 25mm needle length would not ensure deposition of vaccine within the deltoid muscle. METHOD: Non-interventional cross-sectional study in a single site, non-clinical setting in Wellington, New Zealand. Forty participants (29 females), aged ≥18 years, with obesity (BMI>30 kilograms [km]/m[[2]]). Measurements included distance from acromion to injection sites, BMI, arm circumference, and skin-to-deltoid-muscle distance measured by ultrasound at each recommended injection site. RESULTS: Mean (SD) skin-to-deltoid-muscle distances for USA, Australia and New Zealand sites were 13.96mm (4.54), 17.94mm (6.08) and 20.26mm (5.91) respectively, with a mean (95% confidence interval) for the distance between Australia minus New Zealand -2.7mm (-3.5 to -1.9), P<0.001; and USA minus New Zealand -7.6 mm (-8.5 to -6.7); P<0.001. Skin-to-deltoid-muscle distance was greater in females and was positively associated with BMI and arm circumference. The proportions with a skin-to-deltoid-muscle distance >20 mm were 45%, 40% and 15% for the New Zealand, Australia and USA sites respectively. However, the sample size was relatively small, limiting interpretation in specific sub-groups. CONCLUSION: There were marked differences in the skin-to-deltoid-muscle distance between the three recommended injection sites studied. When choosing the required needle length to achieve intramuscular vaccination in obese vaccine recipients, consideration needs to be given to the injection site location, sex, BMI and/or arm circumference, as these factors all influence the skin-to-deltoid-muscle distance. A standard needle length of 25mm may be insufficient to ensure deposition of vaccine into the deltoid muscle in a substantive proportion of adults with obesity. Research is urgently required to determine anthropometric measurement cut-points that can be used to enable appropriate needle length selection to ensure intramuscular vaccination.

COVID-19 vaccination and the skin to deltoid MUSCLE distance in adults with diabetes.

Objectives: To estimate the proportion of adult diabetics with a skin to deltoid muscle distance (SDMD) of > 25 mm, representing a distance greater than the standard needle length used for intramuscular COVID-19 vaccination, and to assess whether anthropometric measurements predict ultrasound SDMD measurements. Design: Non-interventional cross-sectional study. Setting: Single site, non-clinical setting, Wellington, New Zealand. Participants: One hundred participants (50 females) aged at least 18 years diagnosis with diabetes. All participants completed the study. Main outcome measures: The proportions of participants with a SDMD > 25 mm and a SDMD > 20 mm (indicating that the needle would not have penetrated at least 5 mm into the deltoid, which is considered necessary to ensure deposition of vaccine into muscle); the relationship between anthropometric measurements (body weight, body height, body mass index (BMI), skinfold thickness, arm circumference) and SDMD measured by ultrasound. Results: The proportion (95 %CI) of participants with a SDMD > 25 mm was 6/100; 6 % (2.2 to 12.6), and the proportion with a SDMD > 20 mm was 11 % (5.6 to 18.8), of which 9/11 had a BMI ≥ 30 kg/m2 and 9/11 were female. The strongest relationships between anthropometric measurements and SDMD were with arm circumference (r = 0.76, P < 0.001) and BMI (r = 0.73, P < 0.001). Arm circumference and BMI were the best predictors of SDMD measurements with AUC for ROC curves of 0.99 and 0.94 above the 25 mm cut point, 0.97 and 0.89 above the 20 mm cut point respectively. Conclusions: The standard needle length of 25 mm is likely to be insufficient to ensure deposition of COVID-19 vaccine within the deltoid muscle in a small but important proportion of obese adults with diabetes. Arm circumference and BMI are simple measurements that could identify those that need a long needle to ensure successful intramuscular vaccine administration. Funding: Ruth Maud Ring Spencer Estate; Health Research Council of New Zealand (Independent Research Organisation).